The present invention relates to an article comprising paper coated with an aqueous dispersion of polyolefin particles as well as paper coated with a polyolefin film arising from this dispersion.
Coating of paper or paperboard for use in a range of applications is known to provide barriers to a wide range of substances including water, oil, and acids. Typically, high performance coatings, such as those used for paper drink cups, are prepared by extrusion coating or lamination of a melted polyolefin resin directly onto the paper. This process provides continuous coverage over the substrate and prevents liquid placed into the cup from either contaminating the paper or soaking through completely, thereby causing structural failure of the article. Despite the excellent barrier properties of these extrusion coatings, however, limitations in state-of-the extrusion methods require a coating layer that is much thicker than necessary to achieve the desired barrier properties; therefore, polyolefin is wasted. Currently coatings produced by extrusion have a coat weight of at least 15 g/m2, when a significantly lower coat weight is sufficient.
Liquid applied barrier coatings for paper and paperboard have been described in the art. For example, Application No. U.S. 2006/0063877 describes an aqueous dispersion of an olefin copolymer that is useful in paper coating applications to improve brightness. Application No. U.S. 2016/0145806 discloses a dispersible ethylene-(meth)acrylic acid co-polymer for use as a water-repellency layer. Nevertheless, the invention requires separate layers to achieve a broad range of barriers to hydrophobic and hydrophilic materials.
Accordingly, it would be an advance in the art of coated paper or paperboard to reduce the amount of a polymeric barrier layer applied to the substrate without adversely affecting performance.